Visually scored stage 4 sleep, characterized by high-voltage slow EEG, is known to be reduced in schizophrenia. The reduction is substantial, with about 40% of schizophrenic populations showing very low or absent stage 4. The clinical correlates of this striking abnormality of brain function have not yet been studied systematically. Neither has the nature of the EEG abnormality--which could result from reductions in amplitude, density, or period of delta waves--ben established. We propose to seek clinical correlates of altered delta wave activity, defined by visual scoring and computer measurement, in unmedicated patients, and inclinically stable patients receiving neuroleptics. We will also study the effects on EEG of administration and withdrawal from neuroleptics. Careful ratings of clinical symptoms and course will be carried out without knowledge of the results of the sleep studies. These studies will provide new data on the nature, prevalence and clinical correlates of altered delta wave sleep in schizophrenia. REM sleep patterns will also be studied, with computer analysis of EEG waveforms, eye movement activity and temporal pattern. If any of the sleep changes to be investigated prove intrinsically related to the illness, the studies we carry out would yield clues to altered brain mechanisms in a large subgroup of schizophrenic patients.